Which of the following describes a carrier in the context of travel?

In the context of travel, a carrier refers specifically to an entity responsible for transporting passengers or goods from one location to another. This typically includes airlines, which are crucial for air travel, as well as other forms of transportation such as bus or rail services. Carriers are integral to the movement of travelers, providing them with the means to reach their destinations efficiently.

The other options represent different aspects of the travel industry. A service providing accommodations at sea refers to cruise lines, which primarily focus on providing lodging and entertainment rather than transport alone. An establishment offering local tours focuses on guiding visitors through specific attractions or experiences within a region, rather than transporting them between locations. Lastly, a travel agent who offers vacation packages is responsible for planning and selling trips but does not provide the actual transportation services. Thus, the term "carrier" is most accurately aligned with transportation services, making the choice of an airline or transportation service the correct answer in this context.